Magnetic writer with multi-component shielf

ABSTRACT

A writer comprises a main pole, a write gap and a write shield. The main pole has a main pole tip for emitting magnetic flux. The write gap is adjacent the main pole tip along a center axis of the writer. The write shield is spaced from the main pole tip by the write gap. The write shield comprises a first component located above the main pole tip along the center axis and a second component having different magnetic properties from the first component. The second component extends perpendicularly to the center axis from opposing sides of the first component.

BACKGROUND

Magnetic transducers are combined read/write head structures having a writer portion for storing data and a reader portion for retrieving data, and are utilized by a wide variety of magnetic storage systems. The writer typically comprises a main pole (or write pole), a yoke, a back via, and one or more return poles. The main pole and return pole(s) are separated by nonmagnetic write gaps, located at or near an exterior media-facing surface. Magnetic flux is generated by switching the write current in a coil formed about the yoke and main pole. The coil is surrounded by insulating layers that typically extend from the write gap to the back via. Flux loops generated by the write current exit the tip of the main pole, cross into the magnetic medium through the external surface of the transducer, and close through the return pole and back via.

In disc-based magnetic storage systems, the external surface is typically an air-bearing surface (or ABS), and the transducer is typically formed on a slider attached to a suspension assembly and actuator. As the medium tracks past the transducer, it generates windage along the ABS that causes the slider to “fly” just above the surface of the medium. The suspension assembly and actuator position the slider over the medium, allowing the transducer to read and write data along side-by-side tracks that are spaced from one another in the transverse or crosstrack direction.

Data bits are stored by switching the write current as the magnetic transducer flies along the track. The write current determines the flux density and field direction at the main pole tip, and thus the magnetic domain orientation in the medium. In perpendicular writers, flux enters the medium in a substantially perpendicular sense, and the bits are formed perpendicularly along the track. In longitudinal writers, flux enters the medium along the tracking direction, and the bit orientation is along the track.

In general, perpendicular writers allow bits to be packed more closely, increasing areal density as compared to longitudinal designs. To facilitate this configuration, perpendicular media are formed with a top recording layer having high coercivity and unidirectional perpendicular anisotropy, and a soft underlayer (SUL) having high magnetic permeability, low reluctance and high in-plane anisotropy. The end of the main pole facing the recording layer is shaped into a narrow pole tip, which concentrates flux and reduces bit spacing. The return pole is relatively larger, so that the flux spreads out in the SUL before re-crossing the recording layer. This reduces the tendency for rewriting or erasure when the flux loops close back to the return pole.

Magnetic readers utilize read sensors such as magnetoresistive (MR) sensors and multilayer spin valve/giant magnetoresistive (GMR) elements, in which electrical resistance depends strongly upon field strength. The resistance is measured by a sense current, which varies as the reader element tracks across magnetic domain boundaries in the bit pattern, which is read out as a function of the sense current.

In magnetic transducer manufacture, the reader and writer structures are typically formed as a number of closely spaced layers. The reader (or read head) includes a reader element, a bottom shield and a top shield, with the reader element located in a read gap between the bottom and top shields. The writer (or write head) has a main pole (or write pole) formed into a tip at the external media-facing surface, with leading and trailing edges defined by the direction of media motion. Sometimes there are two return poles, one spaced from the leading edge and the other spaced from the trailing edge, with the main pole tip in between. The yoke, coils and back via are usually located away from the external surface and arranged adjacent to or around the main pole, between the first and second return poles.

In side-by-side configurations, the reader and writer are formed in a substantially coplanar sense, with the writer laterally spaced from the reader along the external media-facing surface. In stacked configurations, the writer is typically formed on top of the reader and spaced from the top read shield by a layer of nonmagnetic material. In merged/stacked configurations, which are less common, the reader and writer structures are merged such that the top shield of the reader also functions as a first or bottom return pole for the writer.

In order to increase areal storage density, it is necessary to address the write-plus-erase (WPE) width of the track. The WPE includes not only the useful bit width or write width (WW), where the bit pattern has a high signal-to-noise ratio, but also extends to erase bands located on either side. This creates a need for magnetic writer and transducer designs with reduced erase band width, as compared to total write-plus-erase width WPE.

SUMMARY

This invention concerns a magnetic writer and a magnetic transducer using the writer. The writer has a main pole, a write gap and a write shield. The main pole is formed into a main pole tip for emitting magnetic flux perpendicular to a center axis of the writer. The write gap is formed in a nonmagnetic spacer material located adjacent the main pole tip, and which spaces the write shield from the main pole tip along the center axis.

The write shield comprises a first component and a second component having different magnetic properties from the first component. The first component is formed above the main pole tip along the center axis. The second component extends perpendicularly to the center axis from opposing sides of the first component. The write shield reduces field curvature in the write gap, increasing the ratio of write width to write-plus-erase width for the write head.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a magnetic recording system with an actuator for positioning a magnetic transducer or read/write head on a slider.

FIG. 2 is an external surface view of a magnetic transducer on the slider in FIG. 1.

FIG. 3 is a cross-sectional view of the magnetic transducer in FIG. 2.

FIG. 4 is a schematic illustration of a write bubble structure produced by the magnetic transducer in FIG. 2.

FIG. 5 is an external surface view of an alternate magnetic transducer for the slider in FIG. 1.

DETAILED DESCRIPTION

FIG. 1 is a perspective view of magnetic recording system 10. In this particular embodiment, system 10 comprises a disc drive with actuator assembly 12 for positioning a magnetic transducer on slider 14 over magnetic medium 16. The magnetic transducer has a multi-component write shield for reducing field curvature, as described in more detail below with respect to FIG. 2.

Actuator 12 comprises actuator arm 18 and a suspension with baseplate/mounting block 20, load beam 22 and flexure 24. Load beam 22 is connected to actuator arm 18 at baseplate/mounting block 20, and supports slider 14 on flexure 24. Voice coil motor 26 rotates actuator arm 18 about spindle axis 28, positioning slider 14 with respect to magnetic medium 16.

In the embodiment of FIG. 1, magnetic medium 16 comprises a disc, or a stack of parallel coaxial discs. In operation of system 10, the disc or disc stack rotates about spindle 30 within housing 32, translating magnetic medium 16 with respect to slider 14. Actuator assembly 12 positions slider 14 over magnetic medium 16, allowing the magnetic transducer to perform read and write functions for system 10.

The magnetic transducer on slider 14 writes magnetic data in the form of bits, which are defined by regions of a particular magnetic orientation in medium 16. The bit length is defined along the tracking direction, and determines the linear bit density (typically in bits per inch or BPI, or in metric units such as bits/cm). The crosstrack dimension is the write-plus-erase width (WPE), which includes write width WW and erase bands on either side, and which determines the linear track density (in tracks per inch or TPI, or in tracks/cm). The areal density goes as the product of linear densities TPI and BPI (that is, in bits per square inch or bits/cm²).

Slider 14 utilizes a magnetic transducer with a multi-component write shield, which increases the attainable areal density by reducing magnetic field curvature across the bit pattern. This reduces the relative size of the erase bands on either side of the write width (WW), increasing the maximum potential TPI. The multi-component write shield also produces a more regular write bubble, with less curvature and a more rectangular structure. This improves the packing ratio, increasing the maximum potential BPI and areal density.

FIG. 2 is an external surface view of magnetic transducer 40 for slider 14 of FIG. 1. In this embodiment, magnetic transducer 40 utilizes a stacked read/write head configuration, comprising reader 42 and perpendicular writer 44 with multi-component write shield 46. FIG. 2 shows the external media-facing surface of magnetic transducer 40, which faces a magnetic medium oriented substantially parallel to and above the plane of the figure (see, e.g., FIG. 3).

Reader 42 comprises first (bottom) read shield 52, second (top) read shield 53 and reader element 54. Reader element 54 is located in read gap 58 between read shields 52 and 53, which shield reader element 54 from stray magnetic flux.

Reader element 54 reads magnetic data (bits) along tracking direction S by responding to the magnetic domain orientation in the recording layer of the medium, where the response is based on a magnetoresistive effect such as giant magnetoresistance (GMR) or tunneling magnetoresistance (TMR). In the particular embodiment of FIG. 2, for example, reader element 54 comprises a GMR element or spin valve, and is spaced from shields 52 and 54 by read gap material 58. Alternatively, reader element 54 extends across read gap 58 to contact one or both of shields 52 and 54.

Writer 44 comprises first return pole 56 and a write pole (or main pole) shaped into main pole tip 60 with leading edge 61 and trailing edge 62. Main pole tip 60 is oriented toward the media-facing surface of magnetic transducer 40, and is shielded by multi-component write shield 46 located above trailing edge 62. In some embodiments, writer 44 also comprises second (or trailing) return pole 64, and in further embodiments writer 44 has side shields 65.

Typically, perpendicular writer 44 is spaced from reader 42 by nonmagnetic layer 59. In merged transducer configurations, nonmagnetic layer 59 is absent and top read shield 53 also functions as first (or leading) return pole 56 for write pole 60.

Leading edge 61 and trailing edge 62 of main pole tip 60 are defined in terms of tracking direction S, with magnetic media translation from the bottom to the top of magnetic transducer 40 and writer 44. Magnetic bits are laid down onto the media along main pole trailing edge 62, where the magnetic domains reflect the magnitude and polarity of the flux as the medium passes out of the footprint of main pole tip 60.

In the particular embodiment of FIG. 2, main pole tip 60 is trapezoidal with leading edge 61 tapering toward generally parallel trailing edge 62. In this embodiment, the top pole width at trailing edge 62 (TPWT) is defined in a crosstrack or transverse direction with respect to tracking direction S (that is, perpendicular to center axis A), and the top pole length (TPL) is measured along tracking direction S, from leading edge 61 to trailing edge 62 (that is, parallel to center axis A). Alternatively, main pole tip 60 has a rectangular (untapered) shape, or a more irregular cross section, with transverse (crosstrack) and axial (trackwise) dimensions redefined accordingly.

As shown in FIG. 2, multi-component write shield 46 is a trailing write shield, spaced above trailing edge 62 of main pole tip 60 by write gap material 66. In some designs, multi-component write shield 46 is also referred to as a front shield for main pole tip 60.

Write gap layer 66 spaces trailing edge 62 of main pole tip 60 from multi-component shield 46, and is formed of a nonmagnetic spacer material to reduce flux couplings. Write gap layer 66 defines write gap G along tracking direction S, parallel to center axis A. Additional non-magnetic material 67 spaces main pole tip 60 from first return pole 56, and, depending on configuration, from one or more side shields 65.

First (center) component 48 of multi-component shield 46 is spaced directly above main pole tip 60 by write gap layer 66, along center axis A. The transverse width of first shield component 48 is the front shield notch width (FSNW), transverse to tracking direction S and perpendicular to center axis A. The axial length of first shield component 48 (NWT) is defined along tracking direction S, parallel to center axis A.

Second (left and right) shield components 50, 51 of multi-component write shield 46 are located adjacent first (center) shield component 48. First shield component 48 spaces second shield components 50, 51 in a transverse (crosstrack) direction from center axis A, at least along axial length NWT. Second components 50, 51 extend from opposing side 68, 69 of first component 48, transverse to tracking direction S and perpendicular to center axis A. Typically, first (center) and second (left and right) shield components 48, 50 and 51 are symmetrically arranged about center axis A, but in some embodiments the arrangement is asymmetric.

As shown in FIG. 2, second (left and right) shield components 50, 51 extend behind center shield component 48, opposite write gap material 66. In this embodiment, each of second components 50 and 51 typically comprise the same material, forming a unitary second shield component, with first and second (left and right) sides connecting above center component 48. Alternatively, first component 48 divides second components 50 and 51 into separate left and right sections, resulting in a multi-piece trailing write shield structure with distinct left, center and right pieces (see, e.g., FIG. 5).

Second shield components 50, 51 have different magnetic properties from first shield component 48. In some embodiments, for example, first component 48 is formed of a nonmagnetic material and second components 50, 51 are formed of magnetic materials, such that first component 48 forms a nonmagnetic notch or gap in multi-component write shield 46.

In some of these embodiments, first (center) shield component 48 and write gap layer 66 are comprised of the same materials, but the notch or gap formed by first shield component 48 is nonetheless structurally and functionally distinct from write gap layer 66. In particular, write gap layer 66 spaces multi-component write pole shield 46 from trailing edge 62 of main pole tip 60 in a trackwise direction, while first shield component 48 spaces second shield components 50, 51 (or portions thereof) from center axis A in a crosstrack direction.

From a functional perspective, write gap layer 66 reduces magnetic flux connections to main pole tip 60, while first shield component 48 shapes the field within write gap layer 66, in order to reduce field curvature along trailing edge 62 of main pole tip 60. Field shaping is determined by the geometry and composition of first shield component 48 and second shield components 50, 51, relative to the other elements of writer 44. In particular, the different magnetic properties of first shield component 48 and second shield component 50, 51 are selected to reduce field curvature and increase the attainable storage density, while retaining sufficient effective field strength and gradient to define a readable bit pattern.

FIG. 3 is a cross-sectional view of magnetic transducer 40, taken along center axis A of FIG. 2. Magnetic transducer 40 comprises reader 42 and perpendicular writer 44 with multi-component trailing write shield 46. Magnetic transducer 40 and writer 44 face magnetic medium 70 along external (media-facing) surface 72.

Reader 42 comprises bottom read shield 52, top read shield 53 and reader element 54, as described above. In merged configurations, top read shield 53 also serves as first return pole 56 for writer 44.

Perpendicular writer 44 comprises first return pole 56, main pole 74, multi-component write shield 46 and, in some embodiments, side shields (not shown) and second (trailing) return pole 64, as described above. Main pole (write pole) 74 has a proximal (media-facing) end defined at main pole tip 60. Typical embodiments of writer 44 also comprise back vias 76 and 78, yoke 80 and one or more sets of coils 82 with insulating layers 83.

Medium 70 translates in tracking direction S with respect to magnetic transducer 40 and writer 44. In the particular embodiment of FIG. 3, magnetic medium 70 comprises top recording layer 84, interlayer 85 and soft underlayer (SUL) 86. Recording layer 84 is formed of a magnetically hard, high coercivity material such as an iron oxide, a cobalt alloy or another ferromagnetic material, or a multilayer Co/Pd material with various additives including Cr, Pt, B, Ta and Nb. Interlayer 85 is formed of nonmagnetic material such as a dielectric or nonmagnetic oxide, and SUL 86 is formed of a magnetically soft material with high magnetic permeability, typically CoFe, FeAlN and alloys thereof, or NiFe, CoZrNb, FeTaN and alloys thereof

Coils 82 are formed of a low resistivity material such as Cu, and generate time-varying magnetic flux when energized by a switching write current. Insulating layers 83 are formed of a high resistivity material such as a dielectric, in order to electrically insulate coils 82. In some embodiments, insulating layers 83 are formed of the same or similar materials as write gap layer 66 and nonmagnetic spacers 58, 59 and 67, as shown in FIG. 2. In other embodiments, insulating layers 83 are formed of different materials.

Yoke 80 is formed of a magnetically soft material such as NiFe, in order to improve flux delivery to main pole 74. Main pole 74 is formed of a magnetically soft material with high magnetic moment, such as CoFe, in order to direct the magnetic flux through main pole tip 60 for perpendicular write operations onto magnetic medium 70.

Return poles 56, 64 and back vias 76, 78 are formed of magnetically soft materials such as NiFe, in order to close flux loops from main pole tip 60 through yoke 80 and main pole 74. First back via 76, for example, forms a flux connection between the distal (non media-facing) ends of first return pole 56 and main pole 78. Second back via 78 forms a flux connection between the distal ends of second return pole 64 and yoke 80.

In some embodiments, reader element 54, main pole tip 60 and other elements of magnetic transducer 40 are provided with protective coating 87 at external surface 72. Typical protective coatings include encapsulants, diamond-like coatings (DLCs) and combinations thereof, which protect magnetic transducer 40 and reduce hard particle contamination of magnetic medium 70. In coated embodiments, main pole tip 60 and the proximal (media-facing) end of reader element 54 are spaced from external surface 72 by the coating width. In uncoated embodiments, main pole tip 60 and the media-facing end of reader element 54 are defined along external surface 72.

In perpendicular embodiments of writer 44, magnetic flux loops from main pole tip 60 cross external surface 72 to enter top recording layer 84 of magnetic medium 70 in a substantially perpendicular sense. The flux loops cross interlayer 85 and spread out along bottom layer (SUL) 86, reducing field intensity in order to reduce the tendency for rewriting and erasure when the loops close back across recording layer 84 to return poles 56 and 64. Alternatively, flux enters recording layer 84 in a substantially parallel sense, and interlayer 85 and SUL 86 are sometimes absent.

Multi-component write shield 46 is configured to reduce field curvature proximate main pole tip 60 when writer 44 writes data to magnetic medium 70. Reduced field curvature is reflected in a modified write bubble structure, and in particular by an increased ratio of write width WW to write-plus-erase width WPE. Multi-component write shield 46 thus increases the attainable storage density of writer 44 and magnetic transducer 40, as described below.

FIG. 4 is a schematic diagram illustrating the write bubble structure for perpendicular writer 44 of magnetic transducer 40, as shown in FIGS. 2 and 3 (above) and in FIG. 5 (below). FIG. 4 is taken in a plane parallel to external media-facing surface 72 of FIG. 3, looking down at magnetic medium 70 with tracking direction S from leading edge 61 to trailing edge 62 of main pole tip 60.

The write bubble structure or “footprint” is illustrated by effective field strength (flux) contours 88, which shown field curvature in the region proximate main pole trailing edge 62, where data are recorded onto magnetic medium 70. The flux contours at main pole leading edge 61 are not shown.

Multi-component write shield 46 is spaced above main pole tip 60 along tracking direction S, with leading edge 89 of multi-component write shield 46 separated from trailing edge 62 of main pole tip 60 by write gap G. First (center) shield component 48 is located directly above main pole tip 60 along center axis A, extending across leading edge 89 of multi-component shield 46 with transverse width FSNW, and extending along center axis A with axial length NWT.

Center component 48 of multi-component shield 46 spaces side components 50 and 51 from center axis A at leading edge 89, with side components 50, 51 extending transversely from opposing sides 68, 69 of center component 48. In this particular embodiment, side components 50 and 51 also extend behind center component 48, such that nonmagnetic component 48 forms a notch in magnetic components 50 and 51. The notch has axial length NWT along center axis A, and extends transversely along leading edge 89 of multi-component shield 46 as shown in FIG. 2, above. Note, however, that in the media-facing orientation of FIG. 4, perpendicular writer 44 is reflected about center axis A with respect to FIG. 2. This reverses the left-right orientation of side components 50 and 51, and switches opposing sides 68 and 69 of center component 48.

Multi-component write pole shield 46 reduces field curvature in the write bubble of perpendicular writer 44, particularly along trailing edge 62 of main pole tip 60. Curvature reduction decreases the transverse width of the erase bands relative to write width WW (the useful bit width), reducing ratio R of write width WW to full write-plus-erase width WPE:

$\begin{matrix} {R = {\frac{W\; W}{W\; P\; E}.}} & \lbrack 1\rbrack \end{matrix}$

Typically, ratio R is measured in percent and defined at a particular flux contour, for example at an effective field strength of about 10-12 kOe (for instance, at H≈10 kOe). Increasing R decreases the minimum track spacing transverse to tracking direction S, and increases the maximum attainable TPI.

Curvature reduction also increases the flatness of flux contours 88 across write width WW, including the write gap region between trailing edge 62 of main pole tip 60 and leading edge 89 of multi-component write shield 46. This produces a more regular and rectangular bit structure across write width WW, decreasing the minimum bit spacing along tracking direction S, and increasing the maximum attainable BPI.

Each of these effects increases the maximum bit packing fraction and data storage density. Magnetic field effects are often unpredictable, however, and the benefits depend upon a detailed relationship between multi-component shield 46 and the associated elements of perpendicular writer 44. In particular, the benefits of multi-component shield 46 depend upon the particular geometry of shield components 48, 50 and 51 with respect to main pole tip 60.

In previous baseline designs, main pole tip 60 was formed with trailing edge width TPWT of about 80 nm and axial length TPL of about 200 nm. The trailing edge shield was formed of a single-component material, with write gap G of about 45 nm. Write currents varied between relatively low and relatively high values on the order of 10-100 mA, depending upon writer configuration. With relatively low write currents, for example, write width WW varied from about 54 to about 64 nm and write-plus erase width WPE varied from about 75-100 nm, with ratio R in the range of about 62-72%.

In embodiments of the present design, multi-component shield 46 is formed with nonmagnetic spacer 66 having a transverse width between about half the trailing pole width and the full trailing pole width (½ TPWT<FSNW<TPWT), and an axial length about equal to the write gap or larger (TNW>G, where G<50 nm). This increases ratio R, allowing write-plus-erase width WPE to be decreased without a commensurate increase in write width WW; or, conversely, allowing write width (WW) to be increased without a commensurate increase in write-plus-erase width WPE (see Eq. 1).

Multi-component write shield 46 also allows the main pole trailing edge width (TPWT) to be reduced without substantially decreasing effective field strength and gradient across write width WW, providing additional benefits for storage density. In particular, multi-component write pole 46 allows narrower writer structures to function with lower write currents and smaller write gaps (e.g., about 30 to about 45 nm), providing higher R with narrower WPE, a more uniform bit profile across write width WW, and closer track and bit spacing.

In particular embodiments with main pole trailing edge width TPWT of about 60 nm, for example, write gap G varies from about 30 to about 45 nm and transverse width FSNW of first shield component 48 varies from about 30 to about 60 nm. Depending on write current, this yields write width WW between about 58 and about 61 nm, with write-plus erase width WPE between about 75 and about 83 nm. Ratio R varies from about 73% to about 78%, an improvement of up to 8% over the previous single-component write shield designs.

Additional embodiments of multi-component write shield 46 improve attainable TPI by about 5-10% or about 15-20%, depending upon write gap size and write shield configuration. For first component width FSNW and write gap G of about 30 nm, for instance, the improvement in TPI is about 8% as compared to a single-component write shield design with write gap G≈30 nm, and about 16% as compared to a single-component write shield design with write gap G≈45 nm.

In additional embodiments, with FSNW≈G, ratio R improves by about 3% to about 5% for write gap G≈30 nm, about 5% to about 10% for write gap G≈45 nm, and about 13% to about 16% when write gap G is reduced from 45 nm in the single-component write shield design to 30 nm in the multi-component write shield design. In further embodiments, with FSNW≦2G, ratio R improves by up to 7% for write gap G≈30 nm, up to 10% for write gap G≈45 nm, and up to 15% when write gap G is reduced from 45 nm in the single-component write shield design to 40 nm in the multi-component write shield design.

FIG. 5 is an external surface view of magnetic transducer 40, illustrating an alternate embodiment of writer 44 with multi-component write shield 46. Magnetic transducer 40 comprises reader 42 and writer 44 with multi-component shield 46 for performing perpendicular read/write operations on a magnetic medium that translates in tracking direction S, as described above. In the embodiment of FIG. 5, however, multi-component write shield 46 comprises first (center) shield component 48, second (left and right) shield components 50, 51, and third (outrigger) shield components 90, 91.

As shown in FIG. 5, moreover, second (left and right) shield components 50, 51 do not extend behind first (center) shield component 48. This divides multi-component write shield 46 into a number of discrete left-side and right-side pieces.

First (center) shield component 48 is located directly above main pole 60 along center axis A, forming a center shield piece that is spaced from main pole trailing edge 62 by write gap G in write gap layer 66. Second shield components 50, 51 are spaced from center axis A by first shield component 48, forming left and right shield pieces that extend transversely from opposing sides 68, 69 of first (center) component 48. Third shield components 90, 91 are spaced from first component 48 by second (left and right) components 50, 51, forming outriggers that extend transversely from opposing sides 92, 93 of second shield components 50, 51. In further embodiments, fourth, fifth or additional shield components are similarly arranged about third (outrigger) shield components 90, 91.

Third shield components 90, 91 have different magnetic properties from second shield components 50, 51, in order to further reduce field curvature and further increase ratio R. This improves the maximum potential TPI and BPI, increasing the attainable packing fraction and areal density over a range of write currents and field strengths. In some embodiments, for example, third shield components 90, 91 are formed the same material as center component 48, or of the same or similar (i.e., non-magnetic) materials as write gap 66. Alternatively, third shield components 90, 91 are formed of a material with magnetic properties that are different from those of both first component 48 and second components 50, 51.

In typical embodiments, third shield components 90, 91 are also formed of the same material, such that the left and right outrigger pieces have a symmetric effect. In these embodiments, multi-component shield 46 is sometimes symmetrically arranged about center axis A, as shown in FIG. 5. In other embodiments, however, multi-component shield 46 is asymmetric with respect to the material composition or physical arrangement (or both) of components 48, 50, 51, 90 and 91. In further embodiments, fourth, fifth or additional shield components comprising a range of different magnetic and nonmagnetic materials are also included, utilizing both symmetric and asymmetric configurations.

While this invention has been described with reference to particular embodiments, the terminology used is for the purposes of description, not limitation. Workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention, including the substitution of various equivalents for particular invention elements and adaptations of the invention's teachings to different materials, situations and circumstances. Thus the invention is not limited to the particular embodiments disclosed herein, but encompasses all embodiments falling within the scope of the appended claims. 

1. A writer comprising: a main pole having a main pole tip for emitting magnetic flux; a write gap adjacent the main pole tip along a center axis of the writer; and a write shield spaced from the main pole tip by the write gap, the write shield comprising: a first component located above the main pole tip along the center axis; and a second component having different magnetic properties from the first component, the second component extending perpendicularly to the center axis from opposing sides of the first component.
 2. The writer of claim 1, wherein the first component is formed of nonmagnetic material and the second component is formed of magnetic material.
 3. The writer of claim 2, wherein the first component is symmetrically arranged about the center axis and the second component is symmetrically arranged about the first component and the center axis.
 4. The writer of claim 2, wherein the first component is formed of a same material as the write gap.
 5. The writer of claim 4, wherein the second component extends behind the first component, opposite the write gap, such that the first component forms a nonmagnetic notch in the second component.
 6. The writer of claim 1, wherein the write shield further comprises a third component having different magnetic properties from the second component, the third component extending perpendicularly to the center axis from opposing sides of the second component.
 7. The writer of claim 1, wherein the first component has a transverse width that is between one half a trailing edge width of the main pole tip and the trailing edge width of the main pole tip.
 8. The writer of claim 7, wherein the first component has an axial length that is at least as great as a length of the write gap, wherein the length of the write gap is defined along the axis center axis between the write shield and the main pole tip.
 9. The writer of claim 2, wherein the write shield reduces field curvature adjacent a trailing edge of the main pole tip, as compared to a single-component write shield design in which the first component and the second component are formed of a same material.
 10. The writer of claim 2, wherein the write shield increases a ratio of useful track width to write-plus-erase width for the writer, as compared to a single-component write shield design in which the first component and the second component are formed of a same material.
 11. A magnetic transducer comprising: a reader element for reading magnetic data along a tracking direction; a write pole for writing magnetic data along a trailing edge defined by the tracking direction; a trailing shield spaced above the trailing edge of the write pole by a gap length defined in the tracking direction, the trailing shield comprising: a nonmagnetic material located above the trailing edge of the write pole along the tracking direction; and a magnetic material extending transversely to the tracking direction from opposing sides of the nonmagnetic material.
 12. The magnetic transducer of claim 11, wherein the nonmagnetic material has a transverse width between one half a transverse width of the write pole and the transverse width of the write pole.
 13. The magnetic transducer of claim 12, wherein the transverse width of the write pole is 60 nm or less.
 14. The magnetic transducer of claim 11, wherein the nonmagnetic material has an axial length as defined within the trailing shield, and wherein the axial length is at least as great as the gap length.
 15. The magnetic transducer of claim 14, wherein the gap length is 45 nm or less.
 16. The magnetic transducer of claim 11, wherein the nonmagnetic material and the magnetic material are symmetrically arranged above the write pole, with respect to the tracking direction.
 17. The magnetic transducer of claim 11, wherein the nonmagnetic material shapes a field structure proximate the trailing edge of the write pole, such that a linear storage density of the magnetic transducer is increased by at least five percent with respect to a single-component write shield design in which the first component and the second component are formed of the same material.
 18. A perpendicular writer comprising: a write pole for emitting magnetic flux perpendicular to a tracking direction of the write pole; a nonmagnetic write gap extending from the write pole along the tracking direction; a magnetic write shield spaced from the write pole along the tracking direction by the nonmagnetic write gap; and a nonmagnetic notch formed in the magnetic write shield above the write pole along the tracking direction, in order to reduce curvature of the magnetic flux in the nonmagnetic write gap.
 19. The perpendicular writer of claim 18, wherein the write pole has a trailing edge width of less than 80 nm and the nonmagnetic notch formed in the magnetic write shield has a transverse width of at least half the trailing edge width of the write pole.
 20. The perpendicular writer of claim 18, wherein the nonmagnetic write gap has a length of no more than 45 nm in the trackwise direction and the nonmagnetic notch formed in the magnetic write shield has an axial length at least as great as the length of the write gap. 